I've come to believe that the confounding factors in whether dietary ideas "work" are micronutrients and the gut biome, and these are still really unexplored areas of medicine.
If you have a deficiency of, say, magnesium - that won't be fixed by eating more meat or less sugar, but it might give you strange cravings or bad moods. And if you have a gut that is working inefficiently, it might not adapt well to a high fat diet. And this translates into "bad and good diets", because eating differently reduces the symptoms.
But if your body is generally taking in things efficiently, its macronutrient requirements are going to be mostly proportional to your energy use, and then you can have relatively more protein or relatively more carbs without many ill effects.
So IMHO a decent starting place for dietary change is not really diet itself, but to take a multivitamin, start intermittent fasting, and to get some daily light, full-body exercise. These things start up the flywheel of reducing ongoing deficiencies and increasing selective pressure on the gut.
If you have a deficiency of, say, magnesium - that won't be fixed by eating more meat or less sugar, but it might give you strange cravings or bad moods. And if you have a gut that is working inefficiently, it might not adapt well to a high fat diet. And this translates into "bad and good diets", because eating differently reduces the symptoms.
But if your body is generally taking in things efficiently, its macronutrient requirements are going to be mostly proportional to your energy use, and then you can have relatively more protein or relatively more carbs without many ill effects.
So IMHO a decent starting place for dietary change is not really diet itself, but to take a multivitamin, start intermittent fasting, and to get some daily light, full-body exercise. These things start up the flywheel of reducing ongoing deficiencies and increasing selective pressure on the gut.